Derive a rough subreddit/topic DB, for use in some Toolio demos

[uogbuji]

Grabbed a subset of this wiki thingie, trimmed a few of the more salacious bits (I'm not prude, but also not in the mood to exclude prudes).

subreddits_raw_struct.html.zip

Build on this, with some sort of topic hierarchy and the leaf subreddits list.